Antimicrobials are vital medicines for the treatment of infections in humans. Antimicrobials are also widely used in livestock, fish and plant production. In animals, antimicrobials are used for treatment of infection and prophylactically for disease prevention. In addition, subtherapeutic doses of antimicrobials are used as growth promoters. The result of such widespread use of antimicrobials is an increase in the prevalence of resistant pathogens giving rise to therapeutic failures in humans and animals. Thus, a need exists to develop new and effective antimicrobial agents.